正方形断面柱に発現するウェークギャロッピングにおける振動変位の時間変動

抄録

In this experimental study, fluid dynamic response characteristics of wake galloping between two square prisms of same size in tandem and staggered arrangement to their relative position and free stream velocity were investigated. An immovable square prism of size d was fixed at upstream side and another vibratile square prism was placed at downstream side. The relative position of the vibratile downstream prism to the upstream prism was varied in the range from 1.6 d to 3.1 d in stream-wise direction, and in the range from 0.0 d to 2.1 d in cross flow direction. The vibratile prism at downstream side is elastically supported at it's both end and is restricted to vibrate in only cross-flow direction. Instantaneous displacement of vibratile prism was measured by means of Laser Displacement Anemometer, and degree of vibration was evaluated by rms value of the fluctuating displacement. In addition, the temporal displacement of vibratile prism was evaluated by time variation of the local rms value of the fluctuating displacement. From the experiments, it was found that the local rms value of the fluctuating displacement in quasi-instantaneous is more than twice the rms value of the fluctuating displacement. Also, the classification map with unstable vibration to their relative position at two square prisms was obtained.